Brevity is the Soul of Role Playing

Everything you need to know in three simple sentences.

When it comes to players providing information and backstory for their characters, less is more. While it may help a player to flesh out an elaborate character concept and give them a point of reference for their motivations and personality, bringing a lengthy biography of their character is not going to do much to enhance their experience. Most of their fellow players, and many DMs like myself, would much rather get to know a character first-hand, by travelling with them as a party, then to slog through a strenuous record of their past exploits and defining characteristics.

That's why I encourage players to keep it short and sweet. For my games I ask players to keep it very brief when introducing their characters at the start. Two paragraphs is a decent length of text to offer everything you need to know about a character that you bring to the table. Focus on the most important aspects of the character at hand. What defines them? What is most outwardly apparent? 

There needn't be any "required reading" when it comes to the backstory of your fellow players. I have known some players who brought a novella's worth of information to the table, and it just didn't add much to the experience, nor did it feel good to be obligated to read through the lengthy tome just to know another party member. It's fine to have this information for your own personal reference, but leave it behind at the game table. Convey this information about your character gradually, as it becomes relevant or appropriate to bring it up. Let it flow naturally as part of the overall narrative.

If you use this method, you also have the flexibility to make changes and alterations as you see fit. Anything that hasn't been explicitly stated could still be changed as the story progresses. If you haven't declared your character to be an orphan as you originally planned, then maybe she isn't... maybe her parents live on an island far across the sea... perhaps your story-line crosses over with that of another party member, maybe you shared a class at the academy (intertwining your story with your teammates is always a plus.) By leaving some of these details unsaid at first, it allows you to fill them in as the game goes on.

This somewhat applies to DMs as well. Good DMs should not bombard players with lengthy and long-winded prose when a simple description will suffice. They should leave themselves some openings to fill in the details of your setting as the campaign unfolds. Dungeon Masters: Be clear, be concise. Your players will appreciate you for it, and your game will run more smoothly overall. And encourage your whole game group to follow this advice. Keep the detailed backstory in your personal notes, and don't overwhelm your teammates with a backstory "infodump." If you are conservative with the presentation of information, it will have much more impact whenever it comes up. And your teammates won't get burnt out or bored either. 

Happy ventures!